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Quality Management System
Radiotherapy
On this page
- Introduction
- Acceptance, commissioning and Quality Assurance (QA) - Pre-treatment imaging and simulation
- Acceptance, commissioning and Quality Assurance (QA) - Accelerator beam data commissioning
- Acceptance, commissioning and Quality Assurance (QA) - Treatment planning
- Acceptance, commissioning and Quality Assurance (QA) - Treatment delivery - Teletherapy
- Acceptance, commissioning and Quality Assurance (QA) - Treatment delivery - Brachytherapy
- Acceptance, commissioning and Quality Assurance (QA) - Patient specific QA in IMRT
- Acceptance, commissioning and Quality Assurance (QA) - Data transfer
- Incidents, errors and near misses in radiotherapy
- Quality audit and continuous quality improvement
- Risk analysis
Introduction
RT is a multidisciplinary process; responsibilities are shared between the different disciplines and must be clearly defined. Each group has an important part in the output of the entire process, and their overall roles, as well as their specific QA roles, are inter-dependent, requiring close cooperation. For this purpose a quality system is introduced in each RT department which should encompass a comprehensive approach to all activities in the RT department starting from the moment a patient enters it until the moment he/she leaves, and also continuing into the follow-up period.
It is essential that the performance of radiotherapy equipment remains consistent within accepted tolerances throughout its clinical life, as patient treatments will be planned and delivered on the basis of the performance measurements at acceptance and commissioning. An ongoing QA programme of regular performance checks should therefore be started immediately after the commissioning process.
Important principles
Guidelines should be provided how to establish a common and consistent framework where all steps and procedures in radiotherapy are taken into account. It should specify what the composition, tasks and responsibilities of a multidisciplinary QA team in a RT department should be and how a patient-related QA programme should be structured.
A QA programme of radiotherapy equipment is based on a number of quality control tests that should specify the parameters to be tested, the tests to be performed, the specific equipment to be used, the geometry and frequency of the tests, and the staff performing and supervising the tests. Such a QA programme should furthermore specify the expected results, the tolerance and action levels, as well as the actions required when the tolerance levels are exceeded. It should be kept as simple as possible in order to optimize the time and effort. QA programmes should be tailored to the specific equipment and departmental situation.
Introduction to references
A number of organizations and publications, including the IAEA's Setting up a Radiotherapy Programme: Clinical, Medical Physics, Radiation Protection and Safety Aspects, and the ESTRO Booklet, have given background discussion and recommendations on the structure and management of a QA programme or quality system. After explaining the need for QA in radiotherapy, Chapter 12 in the IAEA Radiation Oncology Physics Handbook discusses in detail a number of QA programmes, including patient-related QA procedures.
As elucidated in Chapter 12 of the IAEA Handbook and in the IAEA publication Setting up a Radiotherapy Programme, a QA programme for equipment is part of a broader QA system of a radiotherapy department. After explaining the need for QA in radiotherapy, Chapter 12 in the IAEA Handbook provides details how an equipment-related QA programme should be structured, and gives a number of examples of QA programmes for radiotherapy equipment.
Acceptance, commissioning and Quality Assurance (QA) - Pre-treatment imaging and simulation
Introduction
Patient data acquisition is an important part of the RT process, since reliable data are required for treatment planning purposes and allow for a treatment plan to be properly carried out. Patient data acquisition includes identification of the target volumes and OARs, determination of patient treatment position, determination and verification of treatment field geometry, and the generation of radiographs or DRRs for each treatment beam for comparison with portal images. For this purpose dedicated equipment for radiotherapy simulation has been developed. Conventional simulation systems are based on treatment unit geometry in conjunction with diagnostic radiography and fluoroscopy systems. Modern CT simulation systems are based on CT images using special software, often available in a 3D treatment planning system.
Imaging has become the primary source of information in the design of radiation therapy. It is required for delineation of target volumes and organs at risk, as well as for computerized treatment planning. As such, it is of critical importance that the signal contained in these images is well understood, and the spatial distribution is precise and accurate. Failure in this aspect can result in serious deleterious effects including failure to control the disease and/or induction of unforeseen toxicities. In addition to planar x-ray imaging and X-ray computed tomography (CT), magnetic resonance imaging (MRI) plays an important role in defining the location and local extent of disease. Also positron emission tomography (PET) is playing an increasing role in the radiation therapy treatment planning process since the introduction of dedicated hybrid PET-CT simulators.
A QA programme in diagnostic radiology serves to ensure that the diagnostic images produced are of sufficiently high quality so that they reliably provide adequate diagnostic information with both the lowest possible cost and the least possible exposure of the patient to radiation. A QA programme of imaging equipment used in radiotherapy should not only address image quality but also geometry, including laser/couch and other geometric alignment. Furthermore, if CT data are used for treatment planning, the consistency of the electron density values across the CT, treatment planning system (TPS), and digitally-reconstructed radiographs (DRRs) should be verified.
Important principles
Patient data requirements for treatment planning include outlining the external shape of the patient for all areas where the beams enter and exit, and in adjacent areas. Targets and internal structures must be outlined in order to determine their shape and volume for dose calculation. Electron densities for each volume element in the dose calculation matrix must be determined if a correction for heterogeneities is to be applied. Transverse CT scans contain all information required for complex treatment planning and form the basis of CT-simulation in modern radiotherapy treatment. Immobilization devices serve not only to immobilize the patient during treatment, but also provide a reliable means of reproducing the patient position from treatment planning and simulation to treatment, and from one treatment to another.
Before the equipment starts to be used to image patients, safety tests should be performed at commissioning. Some of these tests are necessary to set up the baseline values needed for the periodic QA programme. In addition to its role in structure delineation, CT is the primary modality for treatment simulation and treatment planning, including dose calculation. The role of CT in simulation requires that the geometry of the image is faithfully representing the object, both at the CT scanner and after transfer to the treatment planning system (TPS). The role of CT in dose calculation means that an appropriate CT number-to-electron-density conversion is developed and tested in the TPS, both for validation of the density of the object being scanned, as well as for the effect of heterogeneities on the dose calculation algorithm.
Imaging equipment used in radiotherapy is often shared between diagnostic radiology, nuclear medicine and radiotherapy departments. Depending on the local situation, QA tests will therefore also be performed by the medical physicist responsible for its main clinical use.
Introduction to references
A general discussion of the various aspects of treatment preparation including patient data acquisition, simulation and immobilization is presented in Chapter 7 of the IAEA Radiation Oncology Physics Handbook.
Extensive information on imaging equipment is provided in the IAEA Handbook on the Physics of Diagnostic Radiology. The report of the Consultant's Meeting provides an overview of current use and future developments of imaging in radiotherapy. The report of AAPM Task Group 66 discusses image acquisition, image transfer, treatment planning and DRR generation for CT simulators.
The report of the Consultant's Meeting provides an overview of developments in imaging in radiotherapy and provides a number of guidance documents for QA of imaging equipment. Comprehensive guidelines for the QA of CT simulators and the CT-simulation process are given in the AAPM Task Group Report 66. Further guidelines for QA of imaging equipment can be found in the IAEA Radiation Oncology Physics Handbook (particularly chapter 12), and in the IAEA Human Health Series No. 19 publication.
Acceptance, commissioning and Quality Assurance (QA) - Accelerator beam data commissioning
To be developed
Acceptance, commissioning and Quality Assurance (QA) - Treatment planning
Introduction
Quality assurance of a treatment planning system (TPS) concerns tests of the anatomical description of a patient, the beam description and the dose calculations. The first task for the physicist is to understand in detail how the treatment planning software functions. It must be clear from the documentation accompanying the software package as well as from the literature how the various steps in the dose calculation of a specific treatment technique are performed. In the past some irradiation accidents happened, which were related to the misuse of treatment planning equipment. Good training, as well as the availability of well-documented quality assurance procedures, have a huge impact in preventing planning errors.
After the installation of a treatment planning system (TPS) in a hospital, acceptance testing and commissioning of the system is required, i.e., a comprehensive series of operational tests has to be performed before using the TPS for treating patients. These tests do not only serve to ensure the safe use of the system in the clinic, but also help the user in appreciating the possibilities of the system and understanding its limitations. Because of the complexity and magnitude of the testing required, coordinating these activities with the vendor and with institutions having the same system provides valuable information and saves a lot of duplication of tests.
Quality assurance of a treatment planning system (TPS) concerns tests of the anatomical description of a patient, the beam description and the dose calculations. The first task for the physicist is to understand in detail how the treatment planning software functions. It must be clear from the documentation accompanying the software package as well as from the literature how the various steps in the dose calculation of a specific treatment technique are performed. In the past, some irradiation accidents happened, which were related to the misuse of treatment planning equipment. Good training, as well as the availability of well-documented quality assurance procedures, have a huge impact in preventing planning errors.
Important principles
Efforts should concentrate on testing those aspects relevant for the treatment techniques applied in a specific institution. The overall accuracy of the 3D dose calculation in an irradiated patient is determined by the accuracy of the imaging (patient) information, the beam description and the dose calculation algorithm. The QA of a 3D TPS to be used for IMRT not only consists of verifying the algorithms in the system, but is a combination of testing simultaneously the planning and delivery of IMRT. Such an IMRT QA programme depends very much on the local situation and requires a lot of effort in addition to other QA tests of a 3D TPS. Specific QA tests of a TPS for brachytherapy include verification of the data describing these sources in the planning system and checking the calculated dose distributions against an atlas.
The purpose of acceptance testing is to demonstrate to the user at the hospital that the TPS meets the specifications as defined by the user and/or the manufacturer, and that the results with the hardware and software as installed at the user's site are consistent with the type tests performed previously by the manufacturer at the factory. Commissioning of a TPS involves the user to obtain, usually by measurement, very specific data that are needed for the proper functioning of the dose calculation algorithms for the radiation therapy machine that is used to treat patients in the user's clinic.
Efforts should concentrate on testing those aspects relevant for the treatment techniques applied in a specific institution. The overall accuracy of the 3D dose calculation in an irradiated patient is determined by the accuracy of the imaging (patient) information, the beam description and the dose calculation algorithm. The QA of a 3D TPS to be used for IMRT not only consists of verifying the algorithms in the system, but is a combination of testing simultaneously the planning and delivery of IMRT. Such an IMRT QA programme depends very much on the local situation and requires a lot of other efforts in addition to further QA tests of a 3D TPS. Specific QA tests of a TPS for brachytherapy include verification of the data describing these sources in the planning system and checking the calculated dose distributions against other information, e.g. an atlas of pre-calculated data. Diagnostic images and therefore diagnostic devices (CT, CT-PET, MRI scans) should also undergo a specific process of QA, as sources of images for the treatment plan preparation. For more information about these aspects please refer to this part of the website.
Introduction to references
Several reports exist that provide a comprehensive set of QA tests of a 3D TPS including IAEA Report TRS 430, ESTRO Booklet No. 7 and NCS Report No. 15. These tests concern both dosimetric as well as non-dosimetric issues such as verification of anatomy description. ESTRO Booklets No. 8 and No. 9 discuss many aspects of brachytherapy and IMRT, respectively, including QA of treatment planning systems for these types of radiotherapy.
Several reports exist that provide a comprehensive set of acceptance and commissioning tests of a TPS including IAEA Report TRS 430. Other reports such as ESTRO Booklet No. 7 and IAEA-TECDOCs-1540 and 1583 allow institutions to perform in a relatively straightforward way a limited number of tests on their TPS to guarantee the correct performance of a number of functions relevant for accurate treatment planning purposes. ESTRO Booklet No. 8 discusses acceptance testing and commissioning of a TPS for brachytherapy. The AAPM TG 119 report provides tests for IMRT commissioning. Additional information can be found in the IAEA Radiation Oncology Physics Handbook.
Several reports exist that provide a comprehensive set of QA tests of a 3D TPS including IAEA Report TRS 430, ESTRO Booklet No. 7 and NCS Report No. 15. These tests concern both dosimetric as well as non-dosimetric issues such as verification of anatomy description. ESTRO Booklets No. 8 and No. 9 discuss many aspects of brachytherapy and IMRT, respectively, including QA of treatment planning systems for these types of radiotherapy. Additional information can be found in the IAEA Radiation Oncology Physics Handbook.
Acceptance, commissioning and Quality Assurance (QA) - Treatment delivery - Teletherapy
Introduction
In-room imaging is expanding rapidly with a variety of technologies being introduced. These systems are critical in the therapy process, as they verify the geometric placement of the radiation beams within the body. Portal imaging, applying either film or electronic portal imaging devices (EPIDs), is currently still the most applied method to verify the position of the bony anatomy, or another surrogate of the target volume, just before or during treatment. A number of other in-room imaging techniques, including 3D and 4D methods, are becoming increasingly available, and will be presented in more detail under IGRT in the Section "Topics of special interest". In vivo dosimetry is often applied as an ultimate check of the actual delivered dose for specific patient groups or for unusual treatment conditions.
A number of national and international protocols exist to guide the physicist in the quality assurance of teletherapy equipment. QA programmes (quality control tests) for teletherapy machines with recommended test procedures, test frequencies, and tolerance and action levels are generally structured according to daily, weekly, monthly, and annual tests. The QA programme needs to be continually updated as new features become available on teletherapy equipment e.g. dynamic wedges, multi-leaf-collimators, pre-treatment imaging systems, motion management systems.
Acceptance testing of teletherapy equipment assures that the mechanical and dosimetric specifications described in the purchase order are fulfilled, and that the equipment is free of electrical and radiation hazards to staff and patients. After acceptance of the equipment, treatment beam characteristics needed for clinical use are established during the commissioning process. These measurements include the determination of the beam characteristics needed to operate a treatment planning system for this particular type of equipment. A more strict definition of commissioning teletherapy equipment is the process of preparing QA procedures, protocols and other types of instructions for clinical service. Clinical use can only begin when the physicist responsible for acceptance testing and commissioning is satisfied with all aspects required for a safe treatment of patients and places therefore a heavy responsibility on the medical physicist for correct performance of these tests.
Important Principles
A disadvantage of portal imaging using the film technique is its off-line character. For this reason EPIDs have been developed to compare on-line or off-line EPID images with digitally reconstructed radiographs (DRRs). Portal imaging may lead to the introduction of correction rules for improvement of positioning accuracy, improvement of patient immobilization, or adjustment of margins. In vivo dosimetry is most often performed using TLD or diodes. Portal images obtained with an EPID can also be related to the dose inside a patient yielding information in 2D or 3D.
A QA programme of teletherapy equipment includes checks of the visual monitoring systems, lasers, output and other beam characteristics, and tests of mechanical characteristics of the gantry, collimator and couch. If a measurement result is within the tolerance level, no action is required; if the measurement result exceeds the action level, immediate action is necessary and the equipment must not be clinically used until the problem is corrected; if the measurement falls between tolerance and action levels, this may be considered as currently acceptable. Inspection and repair can be performed later, for example after patient irradiations. If repeated measurements remain consistently between tolerance and action levels, adjustment is required.
Acceptance tests are generally divided into mechanical checks, dosimetry measurements and safety checks, and are performed in the presence of a representative of the equipment manufacturer. Often some of the beam characteristics acquired during the acceptance testing procedures serve as baseline values to be checked relative to constancy during future dosimetric QA measurements.
Introduction to References
In-room imaging has been discussed in detail in the Report of the Consultant’s meeting. More information on portal imaging can be found in the IAEA Radiation Oncology Physics Handbook. A comprehensive review on the clinical use of in vivo dosimetry with diodes is given in the IAEA Report, ESTRO Booklet and AAPM Report.
In the IAEA Handbook typical examples of QA programmes are given based on the AAPM TG-40 and IPEM reports. The more recent AAPM Task Group Report 142 is an update of the TG-40 Report. It specifies new tests and tolerances and has been considerably expanded as compared with the original TG-40 Report. The recommended tolerances accommodate differences in the intended use of the machine functionality, e.g. for non-IMRT, IMRT, and stereotactic delivery. More information on quality assurance of teletherapy equipment can be found in J. Van Dyk's Compendium and in the IAEA Handbook.
A number of national and international protocols exist to guide the physicist in the performance of acceptance testing and commissioning of teletherapy equipment. The AAPM Task Group 142 Report is an update of the TG-40 Report, specifying new tests and tolerances, and has added recommendations for not only the new ancillary delivery technologies but also for imaging devices that are part of the linear accelerator. The AAPM Task Group 106 Report gives guidelines for equipment and procedures for linear accelerator beam data collection. Additional information can be found in the IAEA Radiation Oncology Physics Handbook.
Acceptance, commissioning and Quality Assurance (QA) - Treatment delivery - Brachytherapy
Introduction
Acceptance testing and commissioning of brachytherapy equipment are generally part of a regular brachytherapy QA programme. These tests concern the various safety systems and physical parameters including source calibration, radioactive decay, linear uniformity of wire sources, source positioning accuracy and timer consistency.
For a safe and accurate dose delivery using brachytherapy many QA issues need to be considered that are different compared to teletherapy such as safety aspects for the patient, the personnel, and the environment. Furthermore, a proper QA programme for brachytherapy consists of tests for both the radioactive sources and the delivery equipment.
Important principles
Source commissioning should include wipe tests for any contamination both on the package surface and of an individual encapsulated source. Furthermore radiation levels should be measured and recorded both at the package surface and at 1 m distance. The uniformity of the distribution of the radioactive material within an encapsulated source should be checked. Brachytherapy sources should have their source strength calibration traceable to a national standards laboratory. Re-entrant or well type ionization chambers are convenient for calibration of either high or low strength sources. Cylindrical ionization chambers in air or in a solid phantom may also be used for the measurement of high strength sources. These procedures are different for the various types of sources used in brachytherapy.
A QA programme of brachytherapy should consider all relevant aspects, including verification of prescription, treatment plan, and treatment delivery, as well as radiation safety. Such a QA programme should include a check list describing in detail the methodology with recommended frequencies and tolerances. The methods applied in the tests must be available in the department in written form and the results of the individual checks must be documented in a logbook. The therapeutic goals of a brachytherapy treatment should determine to what extent a QA programme should be developed, taking into account the safety of the patient on the one hand, and the available time and resources on the other. The agreement on such a programme should be a joint decision between all professionals involved in a brachytherapy treatment.
Introduction to references
In ESTRO Booklet No. 8 separate quality control procedures are given for High dose rate (HDR), Pulsed dose rate (PDR) and Low dose rate (LDR) and permanent implants. A IAEA TECDOC deals with standardization of calibration of the most commonly used brachytherapy sources, including both photon and beta emitting sources. Additional information can be found in the IAEA Radiation Oncology Physics Handbook.
Many QA aspects of brachytherapy equipment are well covered in a number of textbooks, e.g. the IAEA Handbook and J. Van Dyk's Compendium, as well as in reports of national and international organizations as reviewed in ESTRO Booklet No.8. Some of those textbooks consider radiotherapy in general with brachytherapy as one of the topics. Others such as the GEC ESTRO handbook of brachytherapy, are dedicated more specifically to brachytherapy. The AAPM TG 59 Report discusses QA of high dose rate techniques. The IAEA web site document describes briefly various safety aspects of brachytherapy. More general information can be found in J. Van Dyk's Compendium, in the IAEA Handbook, and in the Handbook of Radiotherapy Physics.
Acceptance, commissioning and Quality Assurance (QA) - Patient specific QA in IMRT
To be developed.
Acceptance, commissioning and Quality Assurance (QA) - Data transfer
Introduction
The patient treatment chart is accompanying the patient during the entire process of radiotherapy. Any mistake made at the data entry of the patient treatment chart is likely to be carried through the whole treatment. QA of the patient treatment chart is therefore essential. An independent dose (MU) calculation at one or more points, which is often recognised as an appropriate QA tool for 3D conformal radiotherapy, may also be adequate for IMRT verification in combination with a comprehensive QA programme of linac performance.
Important principles
Treatment charts should be reviewed regularly, and signed and dated by the reviewer. A QA team should define which items are to be reviewed, who is to review them, when are they to be reviewed, the definition of minor and major errors, and what actions are to be taken in the event of errors. Basic components of a patient treatment chart that should be checked include patient name and ID, photograph, treatment summary and treatment planning data. All planning data, as well as modifications entered during the planning and treatment delivery process, should be independently checked. These checks concern verification of plan integrity, and all irradiation parameters including the MU calculation.
Introduction to references
QA of treatment planning and independent MU calculations are discussed in the textbook Handbook of Radiotherapy Physics and in the IAEA Handbook. Guidelines under Acceptance testing, Commissioning and Quality Control of Record and Verify Systems are published in the IAEA Human Health Reports No. 7. ESTRO Booklet 3 provides a comprehensive formalism for independent MU calculations of photon beams.
Incidents, errors and near misses in radiotherapy
Introduction
When considering risks in radiotherapy, it should always be remembered that the patient is also gaining a major potential benefit from the therapy. However, accidents do occur, and in order to prevent future accidents in radiotherapy it is necessary to learn from accidents that have occurred in the past. When aiming to learn from these past accidents, it is of value to analyze the specific case histories and find the causes, contributing factors, actual circumstances of discovering the accident as well as methods for future prevention. Complementing this retrospective approach, it is also of great benefit to use prospective approaches, such as Probabilistic Safety Analysis (PSA) and risk matrices, in order to prevent accidents that have not yet happened, been reported, or where lessons to learn have not been made available.
Accuracy and precision play an important role in radiotherapy. Knowledge of the uncertainties in the delivery of an RT treatment, both in dosimetry and geometry, is important because if a misadministration is significant it results in an under- or overdose resulting in a potential failure to control the disease or an increased risk on normal tissue damage. There is good evidence that differences of 10% in dose are detectable in a number of clinical situations. Modern treatment techniques such as 3D conformal RT and IMRT, having steep dose gradients, require in addition very accurate patient positioning.
Important Principles
A patient receiving therapy with ionizing radiation will be exposed to many potential sources of harm throughout the medical procedures. While the probability of harm occurring might be low, the consequences of that harm can be very serious for the individual patient, considering the high doses involved in radiotherapy and the serious malignant conditions treated in many cases. The combination of the probability of harm occurring and the consequence of that harm, constitutes the risk for the patient. A review of lessons learned from accidents in radiotherapy, indicate that many of these accidents have occurred under certain conditions, which can be grouped into four categories: (1) Working with awareness and alertness: Accidental exposures have occurred due to inattention to details, and lack of alertness and awareness. This condition could also be made worse if the health professionals have to work in circumstances prone to distractions; (2) Procedures: Accidental exposures have occurred when there is a lack of procedures and checks, or when they are not sufficiently comprehensive, properly documented or fully implemented; (3) Training and understanding: Accidental exposures have occurred when there is a lack of qualified and well-trained staff, with necessary educational background and specialised training; (4) Responsibilities: Accidental exposures have occurred when there are gaps and ambiguities in the functions of personnel along the lines of authority and responsibility. In these cases, safety-critical tasks have been insufficiently covered.
In attempting to avoid accidents in radiotherapy, it is very important to study the lessons that can be learned from previous radiotherapy accidents and to ensure that preventive actions are applied in a clinical setting. From the analysis of a number of recent accidents (and incidents) occurring in radiotherapy institutions after the introduction of new technology, it became evident that a considerable number of these accidents were due to insufficient training of the responsible person. Education and training are therefore critical issues for the safe implementation of new technology and should be well thought-out before new tools are installed.
Introduction to References
The Radiation Protection of Patients (RPoP) website contains information to help health professionals prevent accidental exposures in external beam radiotherapy and brachytherapy. This website also contains training material on this topic.
There has also been much guidance and information published by the IAEA on specific radiotherapy safety issues over the last number of years, such as several booklets with information on lessons to learn from specific radiotherapy accidents and safety reports on radiotherapy, all of which are available on the Internet. Furthermore, there are many other publications on this topic, two of which are listed in the "Related links" box on this page.
The key standards in this area are the International Basic Safety Standards for Protection against Ionizing Radiation and for the Safety of Radiation Sources, also known as the International BSS. These standards mark the culmination of efforts that have continued over the past several decades towards the harmonization of radiation protection and safety standards internationally.
Deviations in RT administration have been discussed at many places including the IAEA Handbook, the ROSIS website, and the BIIJ article of Holmberg. A number of accidents in RT have been thoroughly investigated by the IAEA, and the lessons learned from these accidents disseminated. The ICRP has also summarised causes and contributory factors for RT accidents. More recent accidents have been summarised in a new ICRP report, and those that occurred in France by Derreumaux et al..Deviations in IMRT delivery have been presented in the paper by Ibbott et. al. The IAEA initiative SAFRON is a voluntary reporting scheme for radiotherapy accidents, incidents and near-misses.
Quality audit and continuous quality improvement
Introduction
The clinical outcome for a cancer patient receiving radiotherapy can be compromised by the quality of the equipment and processes used to plan and deliver the treatment. Cancer care professionals work hard to ensure that every patient receives the best and most accurate treatment taking into account all aspects of their medical condition. However, even with the best intentions mistakes can occasionally slip through or poor practices adopted. An independent audit is an effective means for verifying and improving the quality of a radiotherapy program.
The optimum clinical outcome for a patient receiving a course of external beam radiotherapy is critically dependent upon the accurate calibration of the treatment unit. Although it is the responsibility of the clinical facility to ensure that all radiation beams are properly calibrated prior to the first treatment and that the output is closely monitored for stability over the lifetime of the device, it is prudent to obtain independent confirmation of calibration accuracy.
It is entirely possible to audit a part of an organization’s operation, for example, in radiotherapy the treatment machine calibration and dosimetric accuracy, or to assess all the processes and equipment employed for the successful treatment of the patient. Given the critical interplay between people and machines in radiotherapy, reviewing all the processes and equipment involved in the care of the patient from referral to discharge provides a more comprehensive overview of programme quality.
Important Principles
A quality audit of a programme has two principal components: a review of the policies, procedures and critical data, and a site visit to confirm that equipment and clinical processes are functioning as they should be. These two fundamentals are sometimes summarized as advice to “say what you do and do what you say”. An audit is typically carried out by an expert team of two or more professionals and can last up to a week. At the conclusion of the process a written report containing an assessment of the current quality of the programme together with suggestions for improvement is submitted to the facility. It is important to note that an audit is specifically not designed for regulatory purposes and the auditors have no power to enforce any actions based on their assessment; they can only report their findings and give recommendations which the audited centre is free to implement or not as they wish.
Various laboratories across the globe offer remote monitoring of therapeutic radiation beams through mailed out thermoluminescence dosimeters or other devices which can store information about the radiation dose they have received. Although typically not as accurate as an on-site dose determination with an accurately calibrated ionization chamber, postal audits are convenient, relatively cheap and can serve to identify treatment machine calibration errors in different irradiation geometries. Particularly when a new technology is being introduced, such as Intensity Modulated Radiation Therapy, mailed out dosimeters can verify that the data in the treatment planning system accurately describes the treatment beam.
The IAEA’s Comprehensive Audit is performed by a team of at least three senior radiotherapy professionals – a radiation oncologist, medical physicist and radiation therapist – who spend 3 – 5 days on site at the facility. The auditors follow a well designed protocol and they have all received additional training in auditing procedures. The audit itself comprises a review of policies and procedures, a review of the treatment planning system database and the quality assurance program as well as in-depth discussions with upper level and front line staff. In all, 37 multi-item checklists are completed during the site review. The medical physicist member of the team also makes dosimetric measurements on the treatment units. A preliminary assessment of the programme is provided to the institution at the conclusion of the visit followed some time later by a detailed written report with recommendations for quality improvement. Adoption of the reviewers’ recommendations is purely at the discretion of the institution.
Introduction to References
The references describe the IAEA approach to quality audits and the QUATRO programme.
Chapter 28 in the book Quality and Safety in Radiotherapy briefly describes the key features of the IAEA’s auditing programmes. Details of the postal dosimetry service and on-site physics audit are also given. The IAEA Dosimetry Laboratory is the centre of the IAEA/WHO Network of Secondary Standards Dosimetry Laboratories which is described in the SSDL Newsletter No. 58. More information about the IAEA program can be found here.
An overview of auditing in general is provided in the text book chapter. Details of the comprehensive on-site auditing process, including the 37 checklists, are provided in the IAEA publication Comprehensive Audits of Radiotherapy Practices: A Tool for Quality Improvements.